Articular chondrocytes are not considered to be ciliated cells; however, we have demonstrated that all canine articular chondrocytes each have 1 cilium. Furthermore, we have documented a complexity of ciliary structure previously unknown. We propose to study the structure and to measure the incidence and orientation of chondrocytic cilia in articular cartilage and tracheal cartilage from adult horses and rabbits. We plan to use serial section electron microscopic techniques and stereological and Bingham distribution analyses. Subsequently we plan to create degenerative joint disease in 6 dogs by pericutaneously severing the cranial cruciate ligament. At 3 time periods post surgery we will measure the effect of degenerative joint disease on the structure, incidence and orientation of chondrocytic cilia with articular cartilage from the non-operated side serving as a control.